The present invention relates to a refrigerant compressor used in a refrigerant cycle of a refrigerator, an air conditioning device or the like, and more particularly to a discharge valve apparatus of a refrigerant compressor in which an operating characteristic of a discharge valve for opening and closing a refrigerant gas discharge port in a compression chamber is improved.
A description will be given of the refrigerant compressor used in the refrigerant cycle of the refrigerator, the air conditioning device or the like which corresponds to a subject of the present invention on the basis of an embodiment of a closed type rotary compressor with reference to FIG. 6. A refrigerant gas having a low temperature and a low pressure flowing within an accumulator 1 is sucked into a cylinder 3 within a closed container 2 through a suction pipe 4. A suction chamber and a compression chamber (none of them are illustrated) sectioned by a vane (not shown) are formed within the cylinder 3 with respect to a roller 6 provided in the crank shaft 5, and the refrigerant gas is introduced to the compression chamber from the suction chamber so as to be compressed, and becomes a refrigerant gas having a high temperature and a high pressure.
Further, the refrigerant gas reaches a discharge muffler 9 via a discharge port 7 of a main frame 16 and a discharge valve apparatus 8A, a part thereof passes through a passage 14 between a stator 11 and a rotor 12 in a motor 10 and another part thereof passes through a passage 15 between the stator 11 and the closed container 2 so as to flow to an upper portion of the motor 10, and the refrigerant gas further flows out of the compressor through a discharge pipe 13.
FIG. 7 is an enlarged cross sectional view of a conventional discharge valve apparatus 8A, and a description will be given of the conventional discharge valve apparatus 8A. the discharge port 7 for the refrigerant gas is formed in the main frame 16. A reed-shaped discharge valve 80 made of a thin sheet member and a valve restricting plate 81 are overlapped with each other, and are adhered to a mounting hole 17 in the main frame 16 by a caulking pin 18. The refrigerant gas compressed in the compression chamber and reaching a predetermined pressure presses up a valve cover 80a of the discharge valve 80 closing the discharge port 7 from the below in the drawing so as to open the discharge port 7, and is discharged to the discharge muffler. At this time, since the discharge valve 80 is adhered to the main frame 16 in one side, a side of the valve cover 80a warps up so as to be brought into contact with the valve restricting plate 81 for restricting an opening amount of the discharge valve 80.
Since the oil mixed into the refrigerant gas is attached to the contact portion at a time when the discharge of the refrigerant gas is finished and the discharge valve 80 is going to move toward the discharge port 7 from the state of being brought into contact with the valve restricting plate 81, the discharge valve 80 is closely attached to the valve restricting plate 81 or a negative pressure is generated in the contact portion between the both. Accordingly, a valve disengagement (a matter that the discharge valve 80 moves apart from the valve restricting plate 81) is deteriorated, and a close delay of the discharge port 7 is generated. When the close delay of the discharge port 7 is generated, the refrigerant gas flows backward to the suction chamber, so that there is caused a reduction of a compression efficiency.
Accordingly, as disclosed in Japanese Utility Model Publication Nos. 57-15400 and 7-54631, in accordance with the conventional art, a plurality of through holes are provided in a thickness direction of the valve restricting plate or a rib recessed into an opposite side to the valve from the contact surface is provided in a longitudinal direction of the valve restricting plate, whereby it is possible to prevent the discharge valve from being closely attached or it is possible to prevent the negative pressure from being generated on the contact surface of the valve with the valve restricting plate, thereby improving the valve disengagement and improving a response of the discharge valve.
However, in the structure in which a plurality of through holes are provided in the thickness direction of the valve restricting plate as mentioned above, since it is necessary to widely increase the thickness in order to maintain a strength of the valve restricting plate, there is a problem that a productivity is deteriorated and a used amount of the material is increased, whereby a cost is increased.
Further, in the structure in which the rib is provided in the longitudinal direction of the valve restricting plate, since the valve restricting plate is required to have a narrow substantially rectangular and smooth warped shape, there is a problem that forming the rib in this shape has an extremely bad workability and it is hard to maintain a shape accuracy, whereby a cost is increased.
An object of the present invention is to provide a refrigerant compressor which can improve a response of a discharge valve while intending to maintain a strength and a workability of a valve restricting plate and an accuracy of finished shape without increasing a thickness.
In accordance with the present invention, there is provided a refrigerant compressor comprises a discharge port constructed in a member forming a compression chamber, a discharge vale formed in a reed shape and constituted by a valve cover portion for opening and closing the discharge port at one end and a fixed portion at another end, and a substantially rectangular valve restricting plate closely fixed to a member forming the compression chamber together with the fixed portion of the discharge valve and restricting an opening amount of a side of the valve cover portion,
wherein a head portion wider than a middle portion of the valve restricting plate is provided in the valve restricting plate in a side with which the valve cover portion of the discharge valve is brought into contact, and a circular through hole is provided in the head portion. Accordingly, it is possible to well apply a back pressure to the valve cover of the discharge valve.
Further, in accordance with the present invention, there is provided a refrigerant compressor comprises a discharge port constructed in a member forming a compression chamber, a discharge vale formed in a reed shape and constituted by a valve cover portion for opening and closing the discharge port at one end and a fixed portion at another end, and a substantially rectangular valve restricting plate closely fixed to a member forming the compression chamber together with the fixed portion of the discharge valve and restricting an opening amount of a side of the valve cover portion,
wherein a head portion wider than a middle portion of the valve restricting plate is provided in the valve restricting plate in a side with which the valve cover portion of the discharge valve is brought into contact, and a circular recess portion and a small hole extending from the recess portion to an opposite side to the contact surface are provided in a side of the contact surface of the head portion. Accordingly, it is possible to well apply a back pressure to the valve cover of the discharge valve.
Further, in accordance with the present invention, there is provided a refrigerant compressor comprises a discharge port constructed in a member forming a compression chamber, a discharge valve formed in a reed shape and constituted by a valve cover portion for opening and closing the discharge port at one end and a fixed portion at another end, and a substantially rectangular valve restricting plate closely fixed to a member forming the compression chamber together with the fixed portion of the discharge valve and restricting an opening amount of a side of the valve cover portion,
wherein a head portion wider than a middle portion of the valve restricting plate is provided in the valve restricting plate in a side with which the valve cover portion of the discharge valve is brought into contact, and a U-shaped notch having an open front end is provided in the head portion. Accordingly, it is possible to well apply a back pressure to the valve cover of the discharge valve.
Further, in accordance with the present invention, there is provided a refrigerant compressor comprises a discharge port constructed in a member forming a compression chamber, a discharge valve formed in a reed shape and constituted by a valve cover portion for opening and closing the discharge port at one end and a fixed portion at another end, and a substantially rectangular valve restricting plate closely fixed to a member forming the compression chamber together with the fixed portion of the discharge valve and restricting an opening amount of a side of the valve cover portion,
wherein a head portion wider than a middle portion of the valve restricting plate is provided in the valve restricting plate in a side with which the valve cover portion of the discharge valve is brought into contact, and a recess portion having a front end open to a side of the contact surface and a circular shape in a side of the fixed portion is provided in the head portion. Accordingly, it is possible to well apply a back pressure to the valve cover of the discharge valve.
Further, in accordance with the present invention, there is provided a refrigerant compressor as recited in each of the inventions mentioned above, wherein an area of the through hole, or the recess portion or the notch in the head portion of the valve restricting plate is in a range between 3 and 50% of an area of the valve cover portion in the discharge valve. Accordingly, it is possible to well apply a back pressure to the valve cover of the discharge valve.
Further, in accordance with the present invention, there is provided a refrigerant compressor as recited in each of the inventions mentioned above, wherein the through hole, or the recess portion or the notch in the head portion of the valve restricting plate is formed by being press molded from the side of the contact surface in the discharge valve. Accordingly, it is possible to prevent a convex shape from being generated on the contact surface.